Catalytic burner for generating gas atmospheres



R. l. RANUM Jan. 9, 1968 CATALYTIC BURNER FOR GENERATING GAS ATMOSPHERES2 Sheets-Sheet 1 Filed Nov. 6, 1963 R. l. RANUM Jan. 9, 1968 3,362,792CATALYTIC BURNER FOR GENERATING GAS ATMOSPHERES Filed Nov. 6, 1963 2Sheets-Sheet 2 United States Patent 3,362,792 CATALYTIC BURNER FORGENERATING GAS ATMOSPHERES Rolf I. Ranum, Benton Harbor, Mich., assignorto Whirlpool Corporation, a corporation of Delaware Filed Nov. 6, 1963,Ser. No. 321,918 8 Claims. (Cl. 23-281) ABSTRACT OF THE DISCLOSURE Acatalytic hydrocarbon fuel burner having a cylindrical catalyst bedwhich is water cooled, and a pressure relief damper which operates undera preselected internal pressure.

Summary of the invention This invention relates to a generator forgenerating an atmosphere containing oxygen, carbon dioxide and inert gasby the low temperature burning of a hydrocarbon fuel in the presence ofair.

As is disclosed in Bedrosian et al. US. Patent No. 3,102,778, assignedto the same assignee as this application, atmospheres of the above typemay be generated by burning under catalytic conditions a hydrocarbonfuel in the presence of air. This atmosphere may then be used forintroduction into an enclosure in which perishable animal and plantmaterials may be stored for long periods of time without seriousdegradation.

In the above patent there is disclosed semi-diagrammatically as anelement of the apparatus a catalytic burner. One of the features of thepresent invention is to provide an improved catalytic burner forgenerating the abovedescribed atmosphere that is lower in oxygen andhigher in carbon dioxide than ordinary air.

Other features and advantages of the invention will be apparent from thefollowing description of one embodiment thereof taken in conjunctionwith the accompanying drawings. Of the drawings:

FIGURE 1 is a longitudinal central sectional View through a catalyticburner embodying the invention.

FIGURE 2 is a side elevational view of the burner of FIGURE 1.

Catalytic burners of this type employ a granular catalyst in which theburning takes place at relatively low temperatures. The low temperaturesare used here in order to prevent the formation of measurable amounts ofoxides of nitrogen which would have a deleterious effect on the productsbeing stored. Catalysts of this type are well known and are commerciallyavailable, being supplied primarily to the petroleum industry forhydrocarbon modification. Typical catalysts used successfully includechrome-alumina and platinum-alumina.

In the illustrated embodiment there is provided a generally cylindricalfirst gas pervious member 10 in the form of a metal screen and a secondgas pervious member 11 also in the form of a metal screen. Outwardly ofthe member If) there is provided an enclosing casing 12 that is alsocylindrical with the casing 12 and screens 10 and 11 being substantiallyconcentric. The outer screen 10 is spaced from the casing 12 in order toprovide a gas space 13 therebetween.

The tops of the screens 10 and 11 are provided with a circular spacer 15and the spacer together with the tops of the screens are enclosed by acap 16 that has an outer flange 17 outwardly of the outer screen 10 andan inner flange 18 inwardly of the inner screen 11. The combination ofthe flanges 17 and 18 and the spacer 15 secures the top of the catalystbed 14.

The top of the cylindrical casing 12 is provided with an outwardlyextending circular flange 19 attached thereto as by welding. This flangein turn is attached to a circular plate top 20 on the burner by a seriesof peripheral spaced screws 21. Between the top 20 and the flange 19 isa sheet 22 of temperature resistant gasket material such as Fiberfrax.The gasket sheet 22 is also between the metal top 20 and the top of thecap 16. The cap 16 is attached to the top 20 by a series of circularlyarranged bolts 23.

The bottom of the cylindrical casing 12 with an outwardly extending thetop flange 19. Attached to this flange as by a series of circularlyarranged screws 25 is a metal orifice housing 26 that is generallycircular and whose sides are located outwardly of the lower end of theouter screen 10. Positioned within the orifice housing 26 is a circularorifice ring 27 which cooperates with the outer side and bottom of thehousing 26 to provide a circular gas flow passage or manifold member 28at the bottom of the apparatus serving as a manifold. This orifice ring27 is of angular construction as shown in FIGURE 1 and cooperates withthe angular outer lower corner of the housing 26 to define the sides ofthe passage 28. The orifice ring 27 is provided with a circularlyarranged series of orifice passages or exit means 29 in its uppersurface that communicate with the gas space 13.

On one side of the orifice housing 26 there is provided a pipeconnection 30 for the inward flow of a hydrocarbon gas and air mixturefor burning in the generator.

Between the orifice ring 27 and the lower end of a bottorn cap 31 thatis similar in construction to the top cap 16 there is provided a sheetof heat resistant gasket material 32 that is similar to the previouslydescribed gasket material 22. A similar sheet of gasket material 33 isprovided between the bottom of the orifice housing 26 and the bottomedge of the ring 27, the bottom of the lower end cap 31 and the innerend of the pipe 30.

As can be seen in FIGURE 1 the bottom cap 31 is exactly the same as theupper cap 16 and is also fastened in place by a series of bolts 34. Bothof the caps serve to keep the two screens 10 and 11 properly spaced fromeach other and to maintain the outer screen 10 properly spaced from thecasing 12 to define the gas and air inlet space 13.

In order to further complete the gas tight sealing there is providedanother annular sheet of gasket material 35 between the bottom flange 24and the tops of the orifice housing 26 and orifice ring 27. This gasketmaterial is the same as that previously described and is held in placeby the screws 25.

As mentioned earlier, the burning of the hydrocarbon fuel in thepresence of air takes place in the catalyst bed 14. The products ofcombustion then flow through the bed into the interior space 36 that iswithin the interior cylindrical screen 11.

This space 36 communicates at the bottom with a right angle elbow 37 ofmetal which has one leg vertically aligned with the axis of the space 36and the other leg 38 extending outwardly.

The bottom of the elbow 37 beneath the horizontal leg 38 is open asindicated at 39. Mounted 'on the bottom of the elbow 37 adjacent theopening 69 is a support 40 that is welded or otherwise attached to theside of the elbow duct 37 that is opposite the leg 3-8. 'Fastened tothis support 40 as by a plurality of screws 41 is a U- shaped knifeedged pivot 42. The pivot 42 has its knife edges 43 extending outwardlyand facing upwardly, as shown in FIGURE 2. Fulcrumed on these knifeedges 43 is a weighted lever 44 having spaced sides 45 each providedwith a V notch 46 and resting on a knife edge 43. The inner end of thislever 44 is provided with a closure cap 47 to which is attached by meansof a bolt 4-8 a circular is provided flange 24 that is similar to gasket49 which is the same as the gasket material previously described and acovering stiffening washer 50. The end of the lever -44 that is oppositethe cap 47 is provided with a weight 51 attached thereto in order tocounterbalance the cap -47 to normally closed position, as shown in thedrawings.

The elbow 37 is provided with a spark plug 52 having the usual wire lead53. The spark plug is used to initiate combustion in the burner.

In practice, the burner bed 14 is operated at less than 2000 andpreferably more than about 1200 F. A satisfactory operating temperaturewithin the bed 1 5 is about 1600 F.

in order to cool the catalyst bed 1'4 and thus keep the temperaturewithin the bed at less than 2000 F., for example, there is provided ahelical coil 54 for a cooling medium such as water. This coil is inintimate contact with the outer surface of the casing 12 and cools thecasing. This casing in turn cools the catalyst bed 14- by absorbing heatthat is radiated from the bed to the casing.

In operation the mixed hydrocarbon gas which may be ordinary fuel gasand air is led in through the pipe and into the gas space 13. From herethe mixture flows into and through the catalyst bed 14- as indicated bythe arrows. The initial ignition takes place within the space 36 andelbow conduit 37 as combustion is initiated by the spark plug 52.Immediately, ignition moves to the inner surface of the bed 14 asdefined by the screen '11 and the hydrocarbon gas burns with a blueflame adjacent the screen 11. This heats the catalyst bed 14 veryrapidly and as soon as the catalyst reaction temperature is reached,which is about 800 F. for natural gas, the combustion moves into the bed14. Thereupon the temperature within the bed rises rapidly and heat thenbegins to radiate to the outer casing 12 which is cooled by thehelically arranged cooling water pipe 54. The temperature within the bed14 continues to rise until the radiation to the casing 12 and heatlosses out the ends of the burner equal the "heat of combustion minusthe heat content of the exhaust gases leaving the conduit 37. ingeneral, with natural gas this will be a temperature of about 1600 P.which is well below the temperature at which nitrogen from the aircombines with oxygen to form the harmful nitrogen oxides.

In the embodiment shown the gas-air mixture is 40 cubic feet per hour ofnatural gas and 440 cubic feet per hour of air with this mixture flowingin through the pipe 30. This is sufficient to produce exhaust gases flowfrom the outlet 38 at the rate of about 400 cubic feet per hour measuredat a temperature of about 1400" F. These conditions are sufficient toproduce an exhaust gas containing about 2.5% oxygen and about 10.5%carbon dioxide.

On rare occasions, particularly when starting up, there may occur anexplosive hash of burning hydrocarbon gas within the space 36 or theoutlet conduit 3'7 which generates considerable pressure. The leverarrangement 44 is provided to relieve this pressure. Thus, whenever suchan explosion occurs the internal pressure pivots the cover 47 outwardlyto expose the opening 39 and thereby vent the explosion. As soon as theexplosive force has ceased the counterweight 51 thereupon pivots thecover cap 47 to its closed position as shown in the drawings.

Having described my invention as related to the embodiment shown in theaccompanying drawings, it is my intention that the invention be notlimited by any of the details of description, unless otherwisespecified, but rather be construed broadly within its spirit and scopeas set out in the accompanying claims.

The embodiment of the invention in which an exclusive property orprivilege is claimed is defined as follows:

1. A catalytic burner for burning a hydrocarbon fuel in the presence ofair, comprising: an outer enclosing first gas pervious member of closedtransverse cross section; an inner enclosing second gas pervious memberalso of closed transverse cross section located within and spaced fromsaid first member to provide space for retaining a bed of catalyst; anenclosing casing around said first pervious member also of closedtransverse cross section spaced from said first member to provide anenclosing fuel-air space; a fuel-air manifold member having exit meanstherein for projecting a fuel-air mixture into said fuel-air spacesubstantially throughout the transverse cross sectional area thereof;and a gas impervious barrier member between said manifold member andsaid bed preventing direct communication between the manifold and thebed.

2. The burner of claim =1 wherein said exit means comprises means forprojecting a plurality of jets inwardly of said fuel-air space andbetween said second pervious member and casing.

3. A catalytic burner for burning a hydrocarbon fuel in the presence ofair, comprising: an outer enclosing first gas pervious member of closedtransverse cross section; an inner enclosing second gas pervious memberalso of closed transverse cross section located within and spaced fromsaid first member to provide space for retaining a bed of catalyst; anenclosing casing around said first pervious member also of closedtransverse cross section spaced from said first member to provide anenclosing fuel-air space; means at one end of said space for projectinga mixture of fuel and air into said space substantially uniformlythroughout the transvere cross sectional area thereof; and means at saidone end for blocking gas flow directly between said means for projectingand said bed of catalyst.

4. A catalytic burner for burning a hydrocarbon fuel in the presence ofair, comprising: an outer enclosing first gas pervious member of closedtransverse cross section; an inner enclosing second gas pervious memberalso of closed transverse cross section located within and spaced fromsaid first member to provide space for retaining a bed of catalyst; anenclosing casing around said first pervious member also of closedtransverse cross section spaced from said first member to provide anenclosing fuel-air space; means for cooling said enclosing casing; meansat one end of said space for projecting a mixture of fuel and air intosaid space substantially uniformly throughout the transverse crosssectional area thereof and adjacent said casing; and means at said oneend for blocking gas flow directly between said means for projecting andsaid bed of catalyst.

5. The burner of claim 4 wherein said projecting means comprises amanifold having jet means for thusly projecting said mixture in aplurality of spaced jets.

o. A catalytic burner for burning a hydrocarbon fuel in the presence ofair, comprising: an outer enclosing first gas pervious member of closedtransverse cross section; an inner enclosing second gas pervious memberalso of closed transverse cross section located within and spaced fromsaid first member to provide space for retaining a bed of catalyst; anenclosing casing around said first pervious member also of closedtransverse cross section spaced from said first member to provide anenclosing fuel-air space; means for introducing a fuel-air mixture intosaid fuel-air space; an exit conduit means from the interior of saidsecond gas pervious member for conveying combustion products from saidinterior; fuel ignition means in said exit conduit means; means formingan opening in said exit conduit; and a normally closed closure for saidopening displaceable under a preselected internal pressure in saidconduit to open said opening and relieve said pressure.

7. The burner of claim 6 wherein said closure is hingedly mounted and iscounterbalanced to closed position.

8. A catalytic burner for burning a hydrocarbon fuel in the presence ofair, comprising: a generally cylindrical essentially vertical outerfirst gas pervious member; a generally cylindrical essentially verticalinner second gas pervious member spaced from said first member toprovide space for retaining a bed of catalyst; a generally cylindricalessentially vertical casing around said first member and spacedtherefrom to provide an enclosing fuel-air space; means for cooling saidenclosing casing; means at one end of said space for projecting amixture of fuel and air into said space substantially uniformlythroughout the transverse cross sectional area thereof and comprising amanifold having jet means for thusly projecting said mixture in aplurality of spaced jets along the inner surface of said casing; an exitconduit means from the interior of said second gas pervious member forconveying combustion products from said interior; fuel ignition means insaid exit conduit means; means forming an opening in said exit conduitmeans; and a normally closed closure for said opening displacea'bleunder a preselected internal pressure in said conduit to open saidopening and relieve said pressure, said closure being hingedly mountedand counterbalanced to closed position.

References Cited UNITED STATES PATENTS 2,626,675 1/ 1953 Maher 23-288 X2,829,954 4/1958 Dailey et al. 23-255 2,833,615 5/1958 Kollgaa'rd 23-258X 2,943,921 7/1960 King 23-288 2,997,374 8/1961 Lavender et al 23-2883,037,244 3/1962 Byrne et al 23-288 3,102,778 9/1963 Bedrosian et al.21-58 15 JOSEPH SCOVRONEK, Primary Examiner.

